Fluorine is a chemical element that is most electronegative of all the chemical elements. Because of this characteristic, fluorine has many unique applications. For example, fluorine has been used in plasma etching of semiconductor wafers for producing processors, memory devices, and/or other microelectronic devices. In another example, compounds of fluorine (e.g., fluoropolymers, potassium fluoride, and cryolite) have been used in anti-reflective coatings and dichroic mirrors because of their unusually low refractive index.
Industrial production techniques of fluorine typically include the electrolysis of hydrogen fluoride (HF) in the presence of potassium fluoride (KF). The hydrogen fluoride required for the electrolysis is typically obtained from phosphate-containing minerals with significant amounts of calcium fluorides (e.g., calcium fluorite, CaF2). Upon treatment with sulfuric acid (H2SO4), the phosphate-containing minerals release hydrogen fluoride as follows:CaF2+H2SO4→2HF+CaSO4 This fluorine production process, however, can be energy intensive because electrolysis requires a large amount of energy to operate. Also, such processes can have high operating costs because of the constant requirement for mineral extraction.
Fluorine can also be obtained as a byproduct of the uranium enrichment process. In nature, uranium exists as about 99.284% of 238U, about 0.711% of 235U, and about 0.0058% of 234U. While 235U can be used as a fuel for nuclear fission, the other isotopes, 238U and 234U, cannot. Thus, uranium-containing minerals must first be enriched in order to have sufficient concentrations of 235U to support nuclear fission. A common byproduct of the uranium enrichment process includes depleted uranium hexafluoride (238UF6/234UF6), which is a radioactive and hazardous compound typically stored at great expense. Accordingly, it may be desirable to utilize this source of fluorine to efficiently and cost effectively produce fluorine on an industrial scale.